Disc brakes are widely used for braking applications in automobiles. A disc brake generally includes a caliper and a rotor. The rotor may be connected to a wheel and/or axle, so the rotor rotates with the wheel. A style of caliper may be an opposed piston caliper. An opposed piston caliper generally includes opposing pistons within opposing piston bores facing opposing surfaces of the rotor. Typically, the opposing pistons are placed so that one or more inner pistons face an inner side surface of a rotor and one or more outer pistons face an outer side surface of the rotor. The one or more inner pistons are in communication with one or more inner brake pads and the one or more outer pistons are in communication with one or more outer brake pads. A braking force may be generated by depressing a vehicle pedal, causing brake fluid to flow into the opposing piston bores which increases pressure on the pistons to result in actuation. Upon actuation, the pistons move toward the rotor, thus squeezing the brake pads against the rotor to create a braking force to either slow or stop rotation of the rotor. Exemplary caliper housings are disclosed in U.S. Pat. Nos. 5,343,985; 7,766,132; 8,701,847; 9,291,224; US Patent Publication No. 2014/0158483; and PCT Publication No. WO 2014/091423; all of which are expressly incorporated herein by reference for all purposes.
Although opposing pistons may be advantageous in providing a stable braking force, some opposed piston calipers may present problems with vibrations, brake squeal, heat displacement, and/or manufacturability. When a braking force is created, a reaction force opposite the braking force is also created. The reaction force may displace the outer body relative to the inner body or vice-versa. This displacement may result in vibrations of the opposing piston caliper. These vibrations may produce a low frequency brake squeal heard within an interior of a vehicle. Additionally, when the brake force is created, the friction generated between the rotor and the brake pads may generate an intense heating of the rotor. If the resulting heat is not sufficiently dissipated, the heat may melt the brake pads and/or the heat may transfer through the pistons to overheat, and even boil, the brake fluid.
It would be desirable to have a bridge structure connecting a multi-piece opposed piston caliper which provides structural reinforcement as in a monoblock opposed piston caliper, while simultaneously allowing for tooling access into the interior of the opposed piston caliper. It would be advantageous to include a reinforcement structure as part of the bridge structure which is able to provide structural rigidity to the caliper housing, thus reducing or preventing displacement of an outer body relative to an inner body. It is also desirable to include sufficient openings in the bridge structure to allow for heat dissipation when a braking force is created but do not interfere with a reinforcing structure to provide sufficient structural integrity to the caliper housing. It would also be beneficial to have a multi-piece caliper housing which provides for the weight reduction benefits of a monoblock caliper housing.